The First Tet Offensive of 1789

On January 19, 1785, Nguyen Hue lured the Siamese into an ambush on the My Tho River in the Rach Gam-Xoai Mut area of present-day Tien Giang province in the Mekong Delta and defeated them. According to Vietnamese sources, only 2,000 Siamese escaped. The remaining Nguyen family members then fled to Siam. The Battle of Rach Gam-Xoai Mut near My Tho City, Dinh Tuong province, was one of the most important in Vietnamese history because it halted Siamese expansion into southern Vietnam and greatly benefited Nguyen Hue, who then emerged as a national hero. The Trinh in the north were unable to capitalize on this situation because of trouble in their own domain. Bad harvests beginning in 1776 led to disorder, and there was a secessionist struggle. Trinh Sam, head of the family, died in 1786, and his two sons, Trinh Khai and Trinh Can, fought one another for the throne. Eventually Trinh Khai took control in the north, but his youth and physical weakness combined to produce governmental paralysis, undoubtedly to the liking of army leaders who had helped install him in power.

Nguyen Hue now took advantage of the situation to try to reunite Vietnam. He marched an army north under the guise of rescuing the Le kings from Trinh control and won considerable popular support by promising food for the peasants. In a brilliant May-June 1786 campaign Nguyen Hue captured first Phu Xuan, then Quang Tri and Quang Binh provinces. By July, Tay Son troops had reached the Red River Delta and defeated the Trinh. King Le Hien Tong reached accommodation with Nguyen Hue by ceding some territory and giving him his daughter Ngoc Han in marriage. Le Hien Tong died in 1787, and his grandson, Le Chieu Thong, succeeded him.

While Nguyen Hue was restoring the Le dynasty in the north, his brothers controlled the rest of the country. Nguyen Hue dominated the area north of the Pass of Clouds (between present-day Hue and Da Nang) from Thanh Hoa; his brother Nguyen Nhac held the center, with his capital at Qui Nhon; and Nguyen Lu controlled the south, from Gia Dinh near Saigon.

Nguyen Anh was again active in the south, in Gia Dinh province, and Nguyen Hue returned there to assist his brothers in putting him down. Nguyen Hue sent the royal elephants south with the Le treasury and then sailed for Phu Xuan. He left behind his lieutenant, Nguyen Huu Chinh, who had deserted the king and joined the Tay Son cause, to defend Thang Long.

Nguyen Huu Chinh, however, took advantage of Nguyen Hue’s absence to advance his own interests. He and King Le Chieu Thong attempted to gain power for themselves, fortifying the north against Nguyen Hue. The Tay Son commander, then at Phu Xuan, sent one of his generals, Vu Van Nham, north with an army to attack Thang Long. In subsequent fighting Nguyen Huu Chinh was killed and the Le king fled north. Having secured the capital, General Vu Van Nham then took power himself, ruling as king. It had occurred to Nguyen Hue that Vu Van Nham might do this, so he sent two other generals, Ngo Van So and Phan Van Lan, after him. They defeated Vu Van Nham and executed him. Nguyen Hue then invited the Le king to return, but he refused.

In the midst of these developments, Nguyen Hue was again forced to shift his attention to the south to deal with Nguyen Anh. Before leaving the north, however, Nguyen Hue ordered the Le palace razed. After sending the royal treasury south by ship, he left behind a garrison of 3,000 men in Thang Long.

King Le Chieu Thong, meanwhile, was in Bac Giang in far northern Vietnam, but he sent his mother and son to China to ask for assistance from the emperor in reclaiming his throne. Sun Shi-yi, the viceroy in Canton and governor of Kwang-tung (Guang dong) and Kwang-si (Guang xi) provinces, supported military intervention in Vietnam. He believed it would be an easy matter for China to establish a protectorate over an area weakened by a protracted civil war. Chinese Emperor Quian-long (Kien Lung, 1736-1796) agreed, but his public pronouncements stressed that the Le had always recognized Chinese hegemony in sending tribute. He said that China was intervening merely to restore the Le to power.

In November 1788, a Chinese expeditionary force commanded by Sun Shi-yi and assisted by General Xu Shi-heng crossed the frontier at Cao Bang, Tuyen Quang and Lang Son. These columns then converged on Thang Long. The Chinese force, estimated at up to 200,000 men, advanced smoothly into Vietnam, and the Chinese troops gave no cause for Vietnamese hostility en route to the capital. In fact, Chinese and Le edicts stating that the intervention was merely to put down the Tay Son usurpers attracted some Vietnamese support. At the same time, the Chinese demonstrated that they were in Vietnam to stay; along the route to Thang Long they established some 70 military storehouses.

At the news of the Chinese invasion, many of the Tay Son troops manning the northern outposts fled. The Chinese easily won a series of small battles in early and mid-December. Faced with overwhelming force, Ngo Thi Nham, a Tay Son adviser, argued for retreat. He pointed out the overwhelming Chinese numbers and that the Tay Son troops were dispirited. He said that northerners were deserting, and that ‘to attack with troops such as these would be like hunting a tiger with a band of goats.’ He also added that defense of the capital would be difficult because the people there were not committed: ‘the danger would then be from within…and no general…could win under those conditions. It would be like putting a lamprey in a basket of crabs.’ Ngo Van So, Nguyen Hue’s commander in the north, agreed, and Ngo Thi Nham then ordered ships loaded with provisions sent south to Thanh Hoa and dispatched the remainder of the Tay Son troops overland to fortify a line from the Tam Diep Mountains to the sea.